Methane Seepage Caused by Gas Hydrate Dissociation in the Mid‐Okinawa Trough Since the Last Glacial Maximum

Abstract

Cold seeps are seafloor expressions of the upward migration of methane-rich gases through marine sedimentary succession (Judd & Hovland, 2009;Suess, 2020). The carbon transferred by this plumbing system from the lithosphere to the oceans constitutes an important part of the global carbon cycle (Ijiri et al., 2018;Smith et al., 2014). This carbon transfer may cause ocean deoxygenation and acidification and amplify climatic warming if it contributed to the atmospheric concentration of greenhouse gas (Biastoch et al., 2011;Dickens, 2003). To clarify the interaction between submarine methane seeps and climatic change, many studies have probed into the geological controls of methane seeping activities. Their results show that the episodic intensification of deep-water gas seepages is often linked to the dissociation of marine gas hydrate, which is a large and unstable inventory of methane (

Variations in deep-sea methane seepage linked to millennial-scale changes in bottom water temperatures ~50–6 ka, NW Svalbard margin

“…Many other explanations have been suggested, viz., changes in hydrostatic pressure (sea level), tectonic activity/isostatic rebound, and sediment loading. However, concrete data from deep ocean sites are few 31,[33][34][35] .…”

“…Facilitated by faults and porous sediments, free and dissolved gas in the pore water can migrate upward through the GHSZ and through overlying sediments with the potential to reach the atmosphere [21][22][23] . Growing concern about the effect of greenhouse gases on the global warming, rising surface and deep ocean temperatures and on the increasing deep-ocean acidi cation [24][25][26] has fostered an intensi ed interest on the future stability of the GHSZ in a warmer ocean 23,[27][28][29][30][31] .…”